Landau-Zener transition (LZT) has been explored in a variety of physical systems for coherent population transfer between different quantum states. In recent years, there have been various proposals for applying LZT to quantum information processing because when compared to the methods using ac pulse for coherent population transfer, protocols based on LZT are less sensitive to timing errors. However, the effect of finite range of qubit energy available to LZT based state control operations has not been thoroughly examined. In this work, we show that using the well-known Landau-Zener formula in the vicinity of an avoided energy-level crossing will cause considerable errors due to coherent oscillation of the transition probability in a single-passage LZT experiment. The data agree well with the numerical simulations which take the transient dynamics of LZT into account. These results not only provide a closer view on the issue of finite-time LZT but also shed light on its effects on the quantum state manipulation.Landau-Zener transition (LZT) has been explored in a variety of physical systems for coherent population transfer between different quantum states. In recent years, there have been various proposals for applying LZT to quantum information processing because when compared to the methods using ac pulse for coherent population transfer, protocols based on LZT are less sensitive to timing errors. However, the effect of finite range of qubit energy available to LZT based state control operations has not been thoroughly examined. In this work, we show that using the well-known Landau-Zener formula in the vicinity of an avoided energy-level crossing will cause considerable errors due to coherent oscillation of the transition probability in a single-passage LZT experiment. The data agree well with the numerical simulations which take the transient dynamics of LZT into account. These results not only provide a closer view on the issue of finite-time LZT but also shed light on its effects on the quantum state manipulation.

arXiv:1502.00884Scientific ReportsFeb 16, 201522 citations

Control of quantum systems

G. Huang

Mar 1, 198013 citations

Investigation of the laser controlled Landau–Zener mechanism in a coupled quantum system

Mehdi Hosseini, Farrokh Sarreshtedari

Transition dynamics of a coupled two-particle quantum system is numerically investigated in a laser controlled Landau–Zener process. The effect of the laser parameters as well as the coupling strength of the particles on the Landau–Zener transition dynamics are investigated and discussed. It is shown that the coupling strength between the particles, which describes the ferromagnetic or antiferromagnetic behavior of the system, interestingly changes the uncoupled system transitions and introduces new intermediate states. The obtained results provide the required controlling parameters for optimal engineering of the quantum states.Transition dynamics of a coupled two-particle quantum system is numerically investigated in a laser controlled Landau–Zener process. The effect of the laser parameters as well as the coupling strength of the particles on the Landau–Zener transition dynamics are investigated and discussed. It is shown that the coupling strength between the particles, which describes the ferromagnetic or antiferromagnetic behavior of the system, interestingly changes the uncoupled system transitions and introduces new intermediate states. The obtained results provide the required controlling parameters for optimal engineering of the quantum states.

Journal of the Optical Society of America BSep 8, 201710 citations

Quantum parameter estimation with the Landau-Zener transition

Jing Yang, Shengshi Pang, Andrew N. Jordan

We investigate the fundamental limits in precision allowed by quantum mechanics from Landau-Zener transitions, concerning Hamiltonian parameters. While the Landau-Zener transition probabilities depend sensitively on the system parameters, much more precision may be obtained using the acquired phase, quantified by the quantum Fisher information. This information scales with a power of the elapsed time for the quantum case, whereas it is time independent if the transition probabilities alone are used. We add coherent control to the system and increase the permitted maximum precision in this time-dependent quantum system. The case of multiple passes before measurement, Landau-Zener-Stueckelberg interferometry, is considered, and we demonstrate that proper quantum control can cause the quantum Fisher information about the oscillation frequency to scale as ${T}^{4}$ , where $T$ is the elapsed time. These results are foundational for frequency standards and quantum clocks.We investigate the fundamental limits in precision allowed by quantum mechanics from Landau-Zener transitions, concerning Hamiltonian parameters. While the Landau-Zener transition probabilities depend sensitively on the system parameters, much more precision may be obtained using the acquired phase, quantified by the quantum Fisher information. This information scales with a power of the elapsed time for the quantum case, whereas it is time independent if the transition probabilities alone are used. We add coherent control to the system and increase the permitted maximum precision in this time-dependent quantum system. The case of multiple passes before measurement, Landau-Zener-Stueckelberg interferometry, is considered, and we demonstrate that proper quantum control can cause the quantum Fisher information about the oscillation frequency to scale as ${T}^{4}$, where $T$ is the elapsed time. These results are foundational for frequency standards and quantum clocks.

arXiv:1612.02390Physical Review AAug 1, 201739 citations

Control of Quantum Systems

Shuang Cong

Wiley eBooksMar 4, 201465 citations

{T}^{4}

, where

T

is the elapsed time. These results are foundational for frequency standards and quantum clocks.